The subject solar collector is preferably a per-se known all-plastic solar collector consisting of modular units comprised of two spaced-apart tubular manifolds, i.e., an inlet manifold and an outlet manifold, interconnected by a plurality of spaced plastic tubulets which, collectively, constitute the active collecting surface of the solar collector.
These basic units are produced to a width of about 30 cm, but may have a length, i.e., a manifold-to-manifold distance of about four meters. To maintain the integrity and orderly appearance of this plurality of tubulets, there are provided further components in the form of a number of spacer bars which, at predetermined intervals, are snapped onto the tubulets of each basic unit. As the narrowest practically useful collector would consist of four basic units, means, per-se known, are provided to produce mechanically strong and hydraulically tight joints between the manifolds of these units.